WO2006030037A1

WO2006030037A1 - Device, method and bag for forming foam cushions for packaging purposes

Info

Publication number: WO2006030037A1
Application number: PCT/ES2004/000373
Authority: WO
Inventors: Domènec FERNÁNDEZ MUÑOZ; Santiago FIGUERAS FARRÉ; Carles Riba Romeva; Xavier Pla Biosca; Carles DOMÈNECH MESTRES; Jan ESQUERRA LLUCIÀ; Joan Rull Duran; Agustí CHICO ROCA; Andreu Sancho Descalzo
Original assignee: Plasfi, S.A.
Priority date: 2004-08-11
Filing date: 2004-08-11
Publication date: 2006-03-23

Abstract

The invention relates to a device, method and bag for forming foam cushions for packaging purposes. The inventive device comprises: means (1, 2, 3) for forming a bag (80) using a tube of flat laminar material (8) from a spool (10), means (4) for transferring the formed bag (80) to a filling zone, means (5, 6) for supporting and opening the bag (80) under a foam-dispensing nozzle (70) in the filling zone, and means (9) for closing the bag (80) once it has been filled. The inventive method comprises the corresponding steps. According to the invention, the bag (80) consists of flat tubular segment comprising folded lateral edges, a sealed base and, close to the upper edge thereof, a second weld line comprising a non-welded segment which is designed to be opened and closed by means of a third weld line that is separate from the second line, such as to form gas outlet passages.

Description

APPARATUS, METHOD AND BAG FOR CUSHION FORMATION

FOAM FOR PACKING

Scope of the invention The present invention concerns in general an apparatus, method and bag for forming foam cushions for packaging, and more specifically, an automatic apparatus and a method for the formation of bags from a sheet of plastic sheet material. flattened, handling said bags and filling them with a synthetic foamy material, as well as a bag formed by such apparatus and used in said method.

Background of the invention

In patents EP-A-0316850 and EP-A-0557956, apparatuses for forming a bag from plastic films are described simultaneously with its filling with foam precursors. In the devices described in these patents there are no mechanisms for opening the bags, since it does not operate with previously formed bags. The procedure consists in depositing the foaming material as the bag is formed, formation that is carried out by means of heat bonding (with electrically heated rollers) along the lateral edges of the two films that will form the bag, in the case of EP-A-0316850, or along a single side when it is a folded sheet, as in EP-A-0557956.

It is contemplated that these longitudinally sealing rollers are separated before sealing the entire length, thus allowing the escape of the gases generated during the formation of the foam. The predetermined amount of the foaming composition is then introduced between the sheets being sealed, so that the convergent arrangement they adopt serves as a guiding funnel of the foaming composition in the resulting bag, minimizing projections and spillage. . Procedures similar to that described (injection of the foam precursors simultaneously with the formation of the bag) can be found in patent applications EP-A-0534457 or EP-A-0395438. In the latter case, an apparatus is presented that allows the bags to be formed from a sheet bent that only requires a side seam. This lateral seam is not carried out continuously but intermittently, so that the escape of the gases generated during the foaming process is facilitated, as the bag being formed is filled. The ventilation of these gases, as mentioned above, seems to be an important element in this type of machines, according to the recovered documents.

In other patents, such as US-A-5335483, the lateral thermal sealing of the sheets that form the bag is replaced by their joining by adhesive tape.

EP-A-0225976 describes a method and an apparatus for forming a foam lining for packaging purposes, which comprises opening a partially formed plastic bag previously, connected in series to a stored supply of bag material. plastic, direct a predetermined amount of foam precursors into the partially formed bag and complete the formation of the bag by sealing it in the area adjacent to the opening, while separating said bag from the stored supply of the bag material.

In more detail, the apparatus comprises rollers that advance a predetermined amount of flattened plastic tube from a stored supply, along a predetermined transport path. In addition, there are thermal sealing means transverse to the path of the flattened tube. These thermal sealing means consist of two sealing edges, upper and lower, so that the upper edge seals the front end of the next bag to be formed while the lower one seals the formed and filled bags. In a particular embodiment, it is contemplated that the lower sealing edge has an interrupted surface, so that the sealing is not complete, enabling openings that allow gases formed during the foaming process to escape, without causing handling or packaging problems during Your job. The apparatus also has means for cutting a transverse groove in the juxtaposed layers of the flattened tube, as well as means for separating both layers in the groove. In this way, an access opening to the interior of the bag defined by the groove and the sealed front end is provided. The means for separating the juxtaposed layers comprise suction cups or suction cups, which are they are located adjacent to the partially formed bag that is to be opened, and can move between a closed and an open position. Finally, the apparatus includes means for directing predetermined amounts of foam precursors into the bag. These means comprise an injection cartridge that can move between an operative position adjacent to the opening and another separate position. The movement of the cartridge to this separate position allows the sealing of the already filled bag and its separation from the tube supply. This separation is carried out by means of the same blade that has served to practice the opening of the bag, a blade that has two portions, a more advanced central and two lateral ones, more retracted. The central one is the one that serves to practice the opening, the lateral ones being those that carry out the final separation of the bag formed and filled with the rest of the supply of flattened tube.

A disadvantage of the apparatus described in the patent cited above is that, when each bag is filled with the foaming material before said bag is separated from the stored supply of the bag material, the bag-forming means and the means of filling cannot constitute independent modular units that can be separated.

EP-A-0926069 is known as an automatic device for the packaging of articles comprising means for preparing bags of plastic material from two superimposed sheets, means for separating the two sheets forming a kind of funnel to effect the filling the articles and finally some means to close the two sheets by welding forming a closed bag with the articles inside. The apparatus uses adhesive elements to grip and separate the two sheets.

US-A-6035606 describes the use of a blower device to inject ionized air into the bag for the elimination of static electricity.

Exhibition of the invention

The present invention provides an apparatus, a method and a bag for forming foam cushions for packaging. The device according to the present invention comprises guiding and advancing means for advancing incremental lengths of a tube of flattened sheet material from a coil, said sheet of sheet material having folded lateral edges and a closed front transverse edge; cutting means to effect a transverse cut in the tube of laminar material in a position away from said closed leading edge to separate a flattened bag in which the closed leading edge constitutes a closed bottom; welding means for effecting at least a first welding line transverse to said sheet of sheet material in a position adjacent to said cut, upstream thereof, in order to form a new closed leading edge that constitutes a closed bottom for a next bag; transfer means for moving said separate flattened bag to a filling area; support means for receiving the flattened bag from said transfer means, holding it by at least two upper holding areas separated at a rear edge thereof and holding it lying in said filling area; opening means for separating at least some areas of facing walls of the bag adjacent to said rear edge between said two upper fastening areas, to form an opening in said bag while being supported by said support means; foam dispensing means for dispensing a predefined amount of a foaming material into the bag through said opening while the bag is held by said support means; and closing means for reuniting said areas of the opposite walls of the bag next to said rear edge thereof to close said opening while the full bag is held by said support means.

Optionally, said welding means are adapted to effect a second welding line transverse to said sheet of sheet material in a position adjacent to said cut, downstream thereof, said second welding line having at least a portion without welding between the two upper fastening areas of the rear edge of the bag. Optionally, said closing means are adapted to effect a third welding line close to said second welding line and downstream of the same, which extends substantially parallel to said portion without welding between the two upper fastening areas, being formed un soldered passages between the second and third welding lines to provide a gas outlet from inside the bag.

The method according to the present invention comprises the steps of: advancing by means of guiding means and advancing incremental lengths of a tube of flattened sheet material coming from a coil, said sheet of sheet material having flattened lateral edges and a closed front transverse edge; by means of cutting means, make a transverse cut in the tube of sheet material in a position away from said closed front edge to separate a flattened bag in which the closed front edge constitutes a closed bottom; carry out by welding means at least a first welding line transverse to said sheet of sheet material in a position adjacent to said cut, upstream thereof, in order to form a new closed leading edge that constitutes a closed bottom for a next bag; transfer said separate flattened bag by transfer means to a filling area; receiving the flattened bag from said transfer means by means of support, holding it by at least two upper holding areas separated at a rear edge thereof and holding it lying in said filling area; separating, by means of opening means, at least some areas of facing walls of the bag adjacent to said rear edge between said two upper fastening areas, to form an opening in said bag while being supported by said support means; dispensing by means of foam dispensing means a predefined amount of a foamy material inside the bag through said opening while the bag • is held by said support means; and bringing together said closing areas of the opposite walls of the bag next to said rear edge thereof to close said opening while the full bag is held by said support means. Optionally, the method comprises performing by said welding means a second welding line transverse to said sheet of sheet material in a position adjacent to said cut, downstream thereof, leaving at least a portion without welding in said second welding line between the two upper fastening areas of the rear edge of the bag. Optionally, said step of bringing the areas of the facing walls together again to close the bag comprises carrying out said third welding line close to said second welding line and downstream of said bag, where said third welding line it extends substantially parallel to said portion without welding between the two upper fastening areas, being formed un soldered passages between the second and third welding lines to provide a gas outlet from inside the bag.

By virtue of the steps of the method of the invention it is possible to group the different systems that constitute the apparatus according to a modular conception to form different units capable of operating independently or in conjunction. Thus, according to an embodiment of the apparatus, said guiding and advancing means, cutting means and welding means together form a modular bag forming unit; said support means, opening means and closing means together form a modular bag handling unit; and said foam dispensing means form a modular foam dispensing unit.

The aforementioned modular units are mounted on independent racks easily separable and adapted to operate independently. For example, the modular foam dispensing unit could operate independently to fill bags held manually under the foaming material outlet, or it could work in conjunction with the mentioned modular bag handling unit, which could handle previously formed bags supplied by a bag feeder, and the modular bag forming unit could work to manufacture bags that would be stored for later storage and filling. Optionally, when the modular units are grouped together to function together, said transfer means are incorporated in said modular bag forming unit.

The bag according to the present invention comprises a tubular portion of flattened sheet material that defines folded side edges; a first transverse weld line next to a bottom edge that constitutes a closed bottom; a second transverse welding line next to an upper edge of the bag; and a non-welded portion in said second weld line between two upper fastening areas suitable for being grasped by upper handling tongs, at least some areas of facing walls of the bag being adjacent to said upper edge between said two upper holding areas, which can be separated to form a filling opening while the bag is held by said upper handling tongs. The bag is adapted to be closed, once filled, by a third welding line close to said second welding line and below it, said third welding line extending substantially parallel to said portion without welding between the two areas of welding. upper fastening, being formed some welded passages between the second and third welding lines that provide a gas outlet from inside the bag.

Brief description of the drawings

The foregoing and other features and advantages of the present invention will be more fully understood from the following detailed description of some embodiments with reference to the attached drawings, in which:

Fig. 1 is a schematic side view of an embodiment of the apparatus of the present invention;

Fig. 2 is an enlarged partial side view of cutting means and welding means for forming bags that are part of the apparatus of Fig. 1;

Fig. 3 is an enlarged detail of Fig. 2 illustrating the operation of the cutting means and the welding means; Figs. 4A and 4B are schematic side views showing transfer means in two different positions for transferring bags from a forming zone to a filling area of the apparatus of Fig.

one ; Fig. 5 is a schematic front view illustrating the arrangement of electrical resistors that are part of the welding means of Figs. 2 and 3; Figs. 6A and 6B are cross-sectional views showing opening means and closing means in two different positions to open and close the bags in a filling area of the apparatus of Fig. 1;

Fig. 7 is a top view of the opening means and closing means of Figs. 6A and 6B and support means;

Fig. 8 is a side view of the opening means and closing means of Figs. 6A and 6B and the livelihoods; Figs. 9A and 9B are schematic views illustrating the operation of drive means for wheels that are part of the opening means of Figs. 6A and 6B;

Fig. 10 is an exploded perspective view showing different modular units that configure the apparatus of Fig. 1; and Figs. 11A, 11B and 11C are perspective views of a bag according to an embodiment of the present invention in different states of preparation, filling and closing.

Detailed description of some exemplary embodiments Referring firstly to Fig. 1, there is shown an apparatus for forming foam cushions for packaging according to the present invention. The mentioned cushions are constituted by bags filled with a synthetic foamy material and are used for packing purposes to cushion possible blows to the objects contained, for example, in cardboard boxes.

The apparatus comprises guiding and advancing means 1 for advancing incremental lengths of a tube of flattened sheet material 8 coming from a coil 10. This tube of flattened sheet material 8 has folded side edges 84 and, at the beginning of each cycle, has a front transverse edge 81 closed by a welding line Ia which is performed at the end of the preceding cycle. Next, downstream in relation to the direction of travel of the flattened sheet material 8, there are cut means 2 adapted to effect a transverse cut in the sheet of sheet material 8 in a position away from said closed leading edge 81. This The cut produces a separate, flattened bag 80, in which said closed leading edge 81 constitutes a closed bottom. Welding means 3 are provided to carry out at least a first welding line 81 a (see also Figs. 11 A, 11 B and 11C) transverse to said sheet of sheet material 8 in a position adjacent to said cut, upstream thereof, in order to form a new closed leading edge 81 that will constitute said closed bottom for the next bag, as mentioned above. To transfer the flattened bag 80, separated, to a filling zone, transfer means 4 are incorporated, and in said filling zone there are support means 5 adapted to receive the flattened bag 80 from said transfer means 4, hold it by at least two upper holding areas 83a, 83b, separated, provided on a rear edge 82 thereof, and hold it lying in said filling area, where opening means 6 are arranged to separate at least some areas 85a, 85b of facing walls of the bag adjacent to said rear edge 82, between said two upper fastening areas 83a, 83b, to form an opening 86 in said bag 80 while being supported by said support means 5. On the area of filled with foam dispensing means 7 to dispense a predefined amount of a foamy material into the bag 80 through said opening 86 while the bag 80 is held by said support means 5, and together with the said opening means 6, closing means 9 are arranged to rejoin said areas 85a, 85b of the facing walls of the bag 80, next to said rear edge 82 thereof, to close said opening 86 while the full bag is held by said support means 5. In the illustrated embodiment, said welding means 3 are adapted to make a second welding line 82a transverse to said sheet of sheet material 8 in a position adjacent to said cut, downstream of it, with the particularity that said second welding line 82a has at least one unbranded portion 82b between the two upper clamping zones 83a, 83b of the rear edge 82 of the bag 80, as can be seen in Figs. 11 A, 11B and 11 C. This non-welded portion is that which will allow the opening means 6 to form the filling opening 86 in the bag 80. The said guiding and advancing means 1 of the sheet of sheet material 8 comprise at least one pair of rollers 11, 12 in mutual tangential contact with interposition of the sheet of sheet material 8, at least one of said rollers 11, 12 being connected to drive means that include an electric motor to rotate it. One or more guide elements 13 are included in the form of a tension wire disposed transversely to the direction of advance of the sheet of sheet material 8 and on which it rests to reduce and / or eliminate an adherent effect produced by a load of static electricity in the sheet of sheet material 8. Although not shown in the drawing, the apparatus may additionally include other guide elements consisting of wires or rods suspended along a part of the vertical section of the sheet of sheet material 8 in parallel to the direction of advance thereof, and brake means to stop unwanted rotation of the coil 10 due to the inertia thereof when its drive means are stopped. In relation to Figs. 2 and 3 the mentioned cutting means 2 are described in greater detail, which comprise a first support 31 located on one side of the sheet of sheet material 8, on which first support 31 are mounted first and second transverse inclined fins 21, 22 which converge towards a transverse groove 20 defined between them. On the other side, opposite, of the sheet of sheet material 8 is a second support 32 on which first and second runners 23, 24 separated by a space 25 are mounted. The first support 31 is attached to a pair of arms 35 articulated with respect to a frame to pivot about an axis 36. Drive means, described in detail below, are adapted to move the first support 31 by a rotation with respect to said axis 36 in order to apply said first and second transverse inclined fins 21, 22 respectively against parallel, facing edges, of said first and second runners 23, 24, trapping between them a portion of the sheet of sheet material 8, which is stretched stretched over said transverse groove 20 in said space 25. Preferably, the first and second runners 23, 24 are of a elastically deformable material. A blade 26 is mounted on a carriage 27 mounted on guides and driven by a motor-reducer 28 to move said blade 26, inserted through the space 25 and the transverse groove 20, along said transverse inclined fins 21, 22 in order to effect said cross-section of the sheet of sheet material 8.

Advantageously, said welding means 3 are associated with cutting means 2 and comprise a first transverse electrical resistance 33 mounted on the first support 31, in a position upstream of the first and second transverse inclined fins 21, 22, so that, by virtue of the said displacement of the first support 31, the resistance 33 is applied and pressed against the first runner 23 with interposition of the sheet of sheet material 8 to form said first welding line 81a.

Optionally, the welding means 3 comprise a second transverse electrical resistance 34 mounted on the first support 31, in a position downstream of the first and second transverse inclined fins 21, 22, to be applied and pressed, by virtue of said displacement of the first support 31, against the second runner 24 with interposition of the sheet of sheet material 8 to form said second weld line 82a transverse to said tube of sheet material 8.

In Fig. 5 the arrangement of the first and second electrical resistors 33, 34 on the first support 31, upstream and downstream of the first and second transverse inclined fins 21, 22, respectively, is shown schematically. In the example of embodiment shown in Fig. 5, the first and second electrical resistors 33, 34 are formed by a single continuous filament passed through guides 37 located in the ends of the first support 31 and with separate ends fixed on the downstream side of the first and second transverse inclined fins 21, 22 to provide in a central part the said interruption 34a. Generally, between the first support 31 and the first and second electrical resistors 33, 34, pads 38 of a slightly elastic material will be arranged.

As best shown in Fig. 3, this arrangement allows moving said carriage 27 carrying the blade 26 while the first and second resistors 33, 34 are applied against the first and second springs 23, 24, respectively, with interposition of the tube of sheet material 8 and while a portion of the tube of sheet material 8 is held extended and tensioned on the transverse groove 20 in said space 25 by the pressure of the first and second transverse inclined fins 21, 22 on the edges of the first and second runners 23, 24, respectively. With this, the cut is made on the trapped portion of the sheet of sheet material 8 simultaneously with the realization of the first and second welding lines 81a, 82a without the passage of the blade 26 producing tensions over the areas of the sheet of sheet material 8 in contact with the first and second resistors 33, 34, where the plastic material of the tube is molten and is prone to tearing.

It will be understood that, although in the illustrated embodiment example it is the first support 31 that moves in relation to the second support 32, which is fixed, it could be the second support 32 that moves in relation to the first support 31 while it was fixed, or that both first and second supports 31, 32 moved simultaneously towards each other with the same result.

In Figs. 4A and 4B show the said transfer means 4, which are linked to the cutting means 2 and welding 3 to use some of their drives in common. Thus, the transfer means 4 comprise first tilting arms 41 articulated with respect to a frame for pivoting about an axis 40. The first tilting arms 41 are equipped at their ends with respective first clamps 43, each of which comprises a pair of jaws 49 articulated with respect to a support 42 and provided with respective mutually engaged toothed sectors next to the respective joints. One of the jaws is driven by an electric motor-reducer 44 and the other is driven by the first one by virtue of said engagement, which allows the first clamps to switch between open and closed positions.

The first rocker arms 41 are fixed to a crossbar or shaft 40 driven by an electric motor 45 to rotate in both directions a suitable angle to swing the first rocker arms 41 between a first position, shown in Fig. 4A, and a second position, shown in Fig. 4B. In said first position, the first tilting arms 41 keep the first clamps 43 in their open position next to the lateral edges 84 of the sheet of sheet material 8 downstream of the cutting means 2 and welding 3. In this first position, when the First clamps 43 move from their open position to their closed position, grab the sheet of sheet material 8 by lateral clamping areas 84a, 84b close to said cutting means 2 and welding just before they make said transverse cut to separate The bag In said second position, first tilting arms 41 has made a rotation around the axis 40 and the flattened bag 80, separated, is held by the first clamps 43 in the filling area in a position suitable for being transferred to said support means 5.

Advantageously, each support 42 on which one of said first calipers 43 is mounted together with its drive motor-reducer 44, is linked to its respective tilting arm 41 so that it can rotate freely with respect to axis 42a, and has a center of masses such that said first clamps 43 maintain a substantially horizontal equilibrium position independently of the angular position of the swing arm 41. Optionally, it is provided that the maintenance of such horizontal position of the first clamps 43 can be achieved or secured by a rod device guide (not shown) attached to the supports 42 articulated to the tilting arms 41.

In addition, it is provided that the apparatus can be operated with coils 10 of flattened sheet material 8 of different widths. To do this, said bar transverse 40 extends over the entire width of the apparatus and the first tilting arms 41 are slidably coupled along the transverse bar 40, and comprise fixing means for fixing the first tilting arms 41 to the transverse bar 40 in some positions selected according to the width of the flattened sheet material 8 used.

At least one lever 46 is fixed to the crossbar 40 arranged to push the first support 31 until it is applied to the second support 32 when the crossbar 40 rotates to swing the first tilting arms 41 from its second position (Fig. 4B) to its first position (Fig. 4A). Preferably, at the end of said lever 46, a wheel 50 adapted to roll on a surface of the first support 31 is arranged. Articulated to the first support 31 is a shoulder 47 provided with a slide opening 48 in which a slide is inserted. 51 fixed to the lever 46. Thus, when the crossbar 40 rotates to swing the first tilting arms 41 from its first position (Fig. 4A) to its second position (Fig. 4B), the lever 46 makes a first part of path during which the slide 51 slides along said slide opening 48 and a second travel part during which the slide 51 abuts the end of the slide opening 48 and the strap 47 pulls the first support 31 to separating it from the second support 32. In some cases it may be desirable to separate the first support 31 from the beginning of the movement of the lever 46 swinging arms 41. For this, one can be arranged or more elastic elements (not shown) connected at one end to the articulated arms 35 or to the first support 31 and at the other end to the frame to push the first support 31 away from the second support 32.

In relation to Figs. 7 and 8 the support means 5 are described below, which comprise a pair of second tilting arms 51, each of which is equipped with a respective second caliper 53 driven by an electric motor-reducer 54 to switch between positions open and closed. The construction of these second clamps is analogous to that described above in relation to the first clamps 43. The aforementioned second tilting arms 51 are arranged to swing freely with respect to respective axes 55 substantially perpendicular to the plane of the bag 80 when it is held in a lying position in said filling area. When the second tilting arms 51 are in a rest situation, that is, in a stable position hanging by gravity, the second clips 53 are in suitable positions to receive the bag 80 delivered by the first clips 43 of the transfer means 4. Thus, when the first pliers 43 have transferred the bag 80 the filling zone, and while still holding the bag 80 by said lateral clamping zones 84a, 84b, the second pliers 53 pass from their open position to their closed position by gripping Ia bag 80 by the upper fastening areas 83a, 83b. With this, the bag 80 is supported by the second pliers 53 in the filling zone and the first pliers 43 can release the bag 80 and return to the welding and cutting zone by means of a movement of the first swinging arms 41. The mentioned capacity of the second tilting arms 51 to freely swing with respect to axes 55 perpendicular to the plane of the bag 80 serves to compensate for a decrease in the transverse length of the rear edge 82 of the bag 80 due to the formation of the opening 86 (Fig. 7 ) by the action of the opening means 6. Referring to Figs. 6A, 6B, 7 and 8, the opening means 6 and the closing means 9 are described below. The opening means 6 comprise first and second wheels 61, 62 mounted to rotate on respective axes in respective first and second supports 65, 66 located on opposite sides of the flattened suspended bag 80. The said first and second supports 65, 66 are mounted to swing with respect to respective first and second parallel axes in a base 170, and comprise respective gearwheel sectors 163, 164 mutually engaged. An electric motor-reducer 165 is connected to rotate the first support 65, which in turn rotates the second support 66 in an opposite direction by virtue of said engagement. The second wheels 61, 62 have respective first and second adherent surfaces 63, 64 on their periphery, preferably comprising a reusable adhesive material, that is, which can be repeatedly adhered and detached a number of times. The operation of said electric motor-reducer 165 displaces the first and second supports 65, 66 between a closed position, in which said first and second adherent surfaces 63, 64 of the second wheels 61, 62 press against each other with interposition of said areas 85a, 85b of the facing walls of the bag 80 adjacent to said rear edge 82 (Fig. 6A), and an open position, in which the first and second adherent surfaces 63, 64 of the second wheels 61, 62 are separated (Figs. 6B and 7) and the areas 85a, 85b of the facing walls of the bag 80 are adhered respectively to said adherent surfaces 63, 64 forming said opening 86 in the bag 80 (shown in dashed lines in Figs. 6B and 7).

The second wheels 61, 62 are associated with respective drive means arranged to rotate the first and second wheels 61, 62 a predetermined angle in a single direction each time they pass from the closed position to the open position, or vice versa. The rotation of said angle has the purpose of using step by step the complete circumference of the first and second adherent surfaces 63, 64 of the first and second wheels 61, 62. The said drag means include, according to an embodiment example, some first and second ratchets associated to each wheel and mounted to act in opposite directions, whose operation is illustrated in Figs. 9A and 9B with respect to the first wheel 61. The ratchet mechanism of the second wheel 62 is similar and its description will be omitted.

In an interior space of the first wheel 61 is housed a first ratchet associated with a lever 67 protruding from the perimeter of the wheel (Fig. 9A). Said lever 67 is displaced by a cam 68 interposed in the path of said lever 67 when the first wheel 61 passes from the closed position to the open position (Fig. 9B). The displacement of the lever 67 rotates the first and second wheels 61, 62 said predetermined angle in one direction. A second ratchet is also housed inside the first wheel 61 and mounted to prevent the rotation of the first wheel 61 in a direction opposite to the first when the lever 67 returns to its initial position by the thrust of an elastic element (not shown ). The first and second ratchets can be of any known type, for example, of balls between wedge surfaces or cogwheel and fastener. Alternatively, the movement of the lever 67 could be carried out when passing from the open position to the closed position with an equivalent result.

It will be understood that, alternatively, the first and second adherent surfaces 63, 64 could be incorporated into respective first and second movable elements different from the first and second wheels 61, 62. For example, each adherent surface could be incorporated into an endless belt mounted between two pulleys or a tape that is unwound from one coil to be wound in another, etc., and such mobile elements may be associated with respective drive means for their displacement a predetermined length in a single direction each time they pass from the closed position to the open position, or vice versa.

Said closure means 9 comprise first and second pusher elements 91, 92 mounted on respective first and second supports 93, 94 located on opposite sides of the flattened suspended bag 80 and actuated to move between an open position, in which said first and second pusher elements 91, 92 are mutually separated by a distance sufficient to allow the formation of said opening 86 in the bag 80, and a closed position in which the first and second pusher elements 91, 92 press against each other with interposition of said areas 85a, 85b of the opposite walls of the bag 80 adjacent to said rear edge 82, closing the opening 86. During the passage from the open position to the closed position, the bag 80 is torn from the adherent surfaces 63 , 64. Optionally, on the first pusher element 91 is mounted a third electrical resistor 90 arranged to be applied and pressed wave against the second pusher element 92, which acts as a runner, to effect a third welding line 82c (Fig. 11C) next to said second welding line 82a and downstream thereof, which extends substantially parallel to said portion without welding 82b between the two upper fastening areas 83a, 83b, forming passages 87a, 87b being formed without welding between second and third welding lines 82a, 82c to provide a gas outlet from inside the bag. The first and second supports 93, 94, on which said first and second pusher elements 91, 92 are installed, are mounted to swing with respect to respective first and second parallel axes and comprise respective gearwheel sectors 193, 194 (Fig. .7) mutually engaged. An electric motor-reducer 195 is connected to rotate the second support 93, which rotates the first support 94 in an opposite direction by virtue of said engagement. According to the particular embodiment shown in the figures, an output shaft 161 of said electric motor-reducer 165 is fixed to the first support 65 of the adherent surfaces and on this output shaft 161 the first support 93 of the pushers can freely rotate , and an output shaft 191 of said electric motor-reducer 195 is fixed to the first support 93 of the pushers and on this output shaft 191 the first support 65 of the adherent surfaces can freely rotate. Thus, both electric motor-reducers 165, 195 are fixed to the base 170 with their mutually aligned output shafts 161, 191, and on said base 170 some shafts 171 are mounted on which the second supports 66, 94 can freely rotate of adherent surfaces and pushers, respectively.

The foam dispensing means 7, shown in Fig. 1, can be of any known type and comprise a foam dispensing nozzle 70 located in said filling zone in a stationary position immediately above the filling zone where said means opening 6 forms the opening 86 in the bag 80 while the bag 80 is held by the support means 5. The synthetic foamy material dispensed by the dispensing means 7 is preferably a polyurethane foam (PUR) formed from a mixture of polyol and isocyanate made in the same dispensing head.

As can be seen in Fig. 10, the apparatus according to an embodiment of the present invention has the guiding and advancing means 1, cutting means 2 and welding means 3 forming together a modular unit for forming bags 101, the support means 5, opening means 6 and closing means 9 together forming a modular bag handling unit 102, and the dispensing means of Foam 7 forms a modular foam dispensing unit 103. These three modular units 101, 102, 103 are mounted on independent racks easily detachable, and adapted to operate independently. When the three modular units 101, 102, 103 are intended to work together, the transfer means 4 are preferably incorporated in said modular bag forming unit 101, which is also mounted on a base 121 that houses different elements such as organs. Power supply, control, component feed for foaming, etc. The method for forming foam cushions for packaging according to the present invention comprises, firstly, advancing by means of guiding and advancing means 1 incremental lengths of a tube of flattened laminar material 8 from a coil 10, having said flattened laminar material tube 8 folded side edges 84 and a closed front transverse edge 81. Next, by means of cutting means 2, cross-section the laminar material tube 8 in a position away from said closed leading edge 81 to separating a flattened bag 80 in which the closed leading edge 81 constitutes a closed bottom, and at the same time carrying out by means of welding means 3 at least a first welding line 81a transverse to said sheet of sheet material 8 in a position adjacent to said cut, upstream thereof, in order to form a new closed leading edge 81 which constitutes a closed bottom for u Next bag 80. Then, transfer by means of transfer means 4 said flattened bag 80, separated, to a filling area, and receive by means of support 5 the flattened bag 80 from said transfer means 4, hold it by at least two areas of upper fasteners 83a, 83b separated at a rear edge 82 thereof and hold it lying in said filling area. Then, by means of opening means 6 separating at least some areas 85a, 85b from facing walls of the bag adjacent to said rear edge 82 between said two upper fastening areas 83a, 83b, to form an opening 86 in said bag 80 while being supported by said support means 5 and dispensing by means of foam dispensing means 7 a predefined amount of a material foaming inside the bag 80 through said opening 86 while the bag 80 is held by said support means 5. Finally, by closing means 9 again to join said areas 85a, 85b of the opposite walls of the bag 80 next to said rear edge 82 thereof to close said opening 86 while the full bag is held by said support means 5.

Optionally, the method comprises carrying by said welding means 3 a second welding line 82a transverse to said sheet of sheet material 8 in a position adjacent to said cut, downstream thereof, leaving at least a portion without welding 82b in said second welding line 82a between the two upper clamping zones 83a, 83b of the rear edge 82 of the bag 80. This un-welded portion 82b serves to provide a reduced opening 86 in relation to the total width of the sheet of sheet material 8. Optionally, Said step of joining again the areas 85a, 85b of the facing walls to close the bag 80 comprises carrying by said closing means 9 a third welding line 82c close to said second welding line 82a and downstream of it, wherein said third weld line 82c extends substantially parallel to said unsealed portion 82b between the two upper fastening zones 83a , 83b, with passages 87a, 87b being formed without welding between the second and third welding lines 82a, 82c to provide a gas outlet from inside the bag.

Said step of making a cross-section in a sheet of sheet material 8 comprises, firstly, trapping a portion of the sheet of sheet material 8 between first and second fins 21, 22 arranged on one side of the sheet of sheet material 8 and about corresponding first and second runners 23, 24 arranged on the other side, opposite, of the sheet of sheet material 8, wherein said portion of the sheet of sheet material 8 is stretched stretched over a transverse groove 20 between said first and second fins 21, 22 in a space 25 between said first and second runners 23, 24. Next, move an inserted blade 26 through said space 25 and said transverse groove 20 along said first and second fins 21, 22 in interference with the portion of the sheet of sheet material 8 disposed there.

Said step of separating at least some areas 85a, 85b from facing walls of the bag 80 to form an opening 86 comprises displacing first and second adherent surfaces 63, 64 to bring them closer together until they are pressed against one another with interposition of said areas 85a, 85b of the facing walls of the bag 80 adjacent to said rear edge 82, and displacing said first and second adherent surfaces 63, 64 to move them away mutually with areas 85a, 85b of the facing walls of the bag 80 adhered to the these until forming said opening 86. The method comprises incorporating said first and second adherent surfaces 63, 64 in respective first and second mobile elements 61, 62, and moving said first and second mobile elements 61, 62 a predetermined length in a single direction every time they move from a closed position to an open position, or vice versa.

Finally, in relation to Figs. 11 A, 11 B and 11C describe the bag according to an embodiment of the present invention. The bag 80 is intended to be filled with a synthetic foamy material to form foam cushions for packaging, and comprises (Fig. 11A) a tubular portion of flattened sheet material defining folded side edges 84, a first weld line 81a transverse next to a closed bottom edge 81 that constitutes a closed bottom, a second transverse weld line 82a next to an upper edge 82 of the bag 80, and an un welded portion 82b in said second weld line 82a between two upper fastening areas 83a, 83b suitable for being grasped by superior handling tongs. At least some areas 85a, 85b of facing walls of the bag, adjacent to said upper edge 82 between said two upper fastening areas 83a, 83b, are adapted to be separated to form a filling opening 86 (Fig. 11 B ) while the bag 80 is held by said upper handling tongs. In addition, the bag 80 is adapted to be closed, once filled, by a third welding line 82c (Fig. 11C) located next to said second welding line 82a and below it. This third welding line 82c is extends substantially parallel to said portion without welding 82b between the two upper clamping zones 83a, 83b, forming passages 87a, 87b being formed without welding between the second and third welding lines 82a, 82c that provide a gas outlet from the inside of The bag.

One skilled in the art will be able to introduce modifications and variations in the examples of embodiment of the apparatus, method and bag described above and shown without departing from the scope of the present invention as defined in the appended claims.

Claims

RE1VINDICATIONS

1.- Apparatus for forming foam cushions for packaging, where said cushions comprise a bag filled with a synthetic foamy material, characterized in that it comprises: guiding and advancing means (1) for advancing incremental lengths of a sheet of sheet material flattened (8) from a coil (10), said flattened sheet material tube (8) having folded side edges (84) and a closed front transverse edge (81); cutting means (2) to effect a transverse cut in the tube of sheet material (8) in a position away from said closed leading edge (81) to separate a flattened bag (80) in which the closed leading edge (81 ) constitutes a closed fund; welding means (3) for effecting at least a first welding line (81a) transverse to said sheet of sheet material (8) in a position adjacent to said cut, upstream thereof, in order to form a new edge closed front (81) constituting a closed bottom for a following bag (80); transfer means (4) for moving said separate flattened bag (80) to a filling area; support means (5) to receive the flattened bag (80) from said transfer means (4), hold it by at least two upper holding areas (83a, 83b) separated at a rear edge (82) thereof and hold it lying in said filling area; opening means (6) for separating at least some areas (85a, 85b) of facing walls of the bag adjacent to said rear edge (82) between said two upper fastening areas (83a, 83b), to form a opening (86) in said bag (80) while being supported by said support means (5); foam dispensing means (7) for dispensing a predefined amount of a foamy material into the bag (80) through said opening (86) while the bag (80) is held by said support means (5) ; Y closing means (9) for rejoining said areas (85a, 85b) of the facing walls of the bag (80) next to said rear edge (82) thereof to close said opening (86) while the bag fills it is sustained by said means of support (5).

2. Apparatus, according to claim 1, characterized in that said welding means (3) are adapted to effect a second welding line (82a) transverse to said sheet of sheet material (8) in a position adjacent to said cut , downstream of the same, said second welding line (82a) presenting at least a portion without welding (82b) between the two upper fastening areas (83a, 83b) of the rear edge (82) of the bag (80).

3. Apparatus, according to claim 1, characterized in that said cutting means (2) comprise a first support (31) on one side of the sheet of sheet material (8) on which first and second inclined fins are mounted cross sections (21, 22) that converge towards a transverse groove (20) defined between them, a second support (32) on the other side, opposite, of the sheet of sheet material (8), on which first and second ones are mounted sufferers (23, 24) separated by a space (25), drive means for displacing at least one of said first and second supports (31, 32) in order to apply said first and second transverse inclined fins (21, 22 ) respectively against parallel, facing edges of said first and second runners (23, 24) trapping between them a portion of the tube of laminar material (8) stretched stretched over said transverse groove (20) in said space (25), and a blade (26) mounted on re a carriage (27) guided and driven to move said inserted blade (26) through the space (25) and the transverse groove (20) along said transverse inclined fins (21, 22) in order to effect said cross section of the sheet of sheet material (8).

4. Apparatus, according to claim 3, characterized in that the welding means (3) comprise a first transverse electrical resistance (33) mounted on the first support (31) to be applied and pressed, by virtue of said displacement of at least one of said first and second supports (31, 32), against the first runner (23) with interposition of the sheet of sheet material (8) to form said first welding line (81a).

5. Apparatus, according to claim 4, characterized in that the welding means (3) comprise a second transverse electrical resistance (34) mounted on the first support (31) to be applied and pressed, by virtue of said displacement of at least one of said first and second supports (31, 32), against the second runner (24) with interposition of the sheet of sheet material (8) to form a second weld line (82a) transverse to said tube of sheet material ( 8) in a position adjacent to the first weld line (81a), downstream of said cut, said second resistance (34) presented at least one interruption (34a) to leave a portion without welding (82b) in said second line of welding (82a) located between the two upper clamping areas (83a, 83b) of the rear edge (82) of the bag (80).

6. Apparatus, according to claim 5, characterized in that said carriage (27) carrying the blade (26) is adapted to be moved while the first and second resistors (33, 34) are applied against the first and second runners (23, 24), respectively, with interposition of the tube of sheet material (8) in order to effect the cutting of the tube of sheet material (8) simultaneously with the realization of the first and second welding lines (81a, 82a) .

7. Apparatus, according to any one of claims 3 to 6, characterized in that said first and second runners (23, 24) are of an elastically deformable material.

8. Apparatus, according to claim 1, characterized in that said opening means (6) comprise first and second adherent surfaces (63, 64) arranged in respective first and second supports (65, 66) located on opposite sides of the flattened bag suspended (80) and actuated to move between a closed position, in which said first and second adherent surfaces (63, 64) press against each other with interposition of said areas (85a, 85b) of the opposite walls of the bag (80) adjacent to said rear edge (82), and an open position, in which the first and second adherent surfaces (63, 64) they are separated and the areas (85a, 85b) of the opposite walls of the bag (80) are adhered respectively to said adherent surfaces (63, 64) forming said opening (86) in the bag (80).

9. Apparatus, according to claim 8, characterized in that said first and second adherent surfaces (63, 64) comprise a reusable adhesive material and are incorporated in respective first and second movable elements (61, 62) associated with respective drag means arranged to move said first and second mobile elements (61, 62) a predetermined length in a single direction each time they pass from the closed position to the open position, or vice versa.

10. Apparatus, according to claim 9, characterized in that said first and second mobile elements (61, 62) are first and second wheels (61, 62) mounted to rotate on respective axes and associated with respective means of drag arranged to rotate the first and second wheels (61, 62) a predetermined angle in a single direction each time they pass from the closed position to the open position, or vice versa.

11. Apparatus, according to claim 10, characterized in that said drive means include a first ratchet associated with a lever (67) that is displaced by a cam (68) interposed in the path of said lever (67) when the first and second wheels (61, 62) pass from the closed position to the open position, or vice versa, to rotate the first and second wheels (61, 62) said predetermined angle in one direction, and a second ratchet mounted to prevent the rotation of the first and second wheels (61, 62) in a direction opposite to the first when the lever (67) returns to its initial position by the thrust of an elastic element.

12. Apparatus, according to claim 11, characterized in that said closing means (9) comprise first and second pusher elements (91, 92) mounted on respective first and second supports (93, 94) located on opposite sides of the flattened bag suspended (80) and actuated to move between an open position, in which said first and second pusher elements (91, 92) are mutually separated by a distance sufficient to allow the formation of said opening (86) in Ia bag (80), and a closed position in which the first and second pusher elements (91, 92) press against each other with interposition of said areas (85a, 85b) of the opposite walls of the adjacent bag (80) to said rear edge (82) closing the opening (86).

13. Apparatus, according to claim 12, characterized in that a third electrical resistor (90) is mounted on the first pushing element (91) arranged to be applied and pressed against the second pushing element (92), which acts as a runner, to effect a third welding line (82c) close to said second welding line (82a) and downstream of it, which extends substantially parallel to said un soldered portion (82b) between the two upper clamping areas (83a, 83b), being formed passages (87a, 87b) without welding between the second and third welding lines (82a, 82c) to provide a gas outlet from inside the bag.

14. Apparatus, according to claim 8, characterized in that said first and second supports (65, 66), on which said first and second adherent surfaces (63, 64) are arranged, are mounted to swing with respect to respective ones first and second parallel axes and comprise respective mutually engaged gearwheel sectors (163, 164), with an electric motor-reducer (165) connected to rotate the first support (65), which rotates the second support (66 ) in an opposite direction, while said first and second supports (93, 94), on which said first and second pusher elements (91, 92) are installed, are mounted to swing with respect to respective first and second parallel axes and they comprise respective gearwheel sectors (193, 194) mutually engaged, with an electric motor-reducer (195) connected to rotate the second support (93), which rotates the first support (9 4) in an opposite direction.

15. Apparatus, according to claim 14, characterized in that said electric motor-reducer (165) has an output shaft (161) integral with the first support (65) of the adherent surfaces and on which the first one can freely rotate support (93) of the pushers, and said electric motor-reducer (195) has an output shaft (191) integral with the first support (93) of the pushers and on which the first support (65) of the adherent surfaces can freely rotate, both electric motor-reducers (165, 195) being fixed to a base (170) with their output shafts (161, 191) mutually aligned , said shafts (171) being mounted on said base (170) with respect to which the second supports (66, 94) of the adherent surfaces and the pushers can rotate freely.

16. Apparatus, according to claim 3, characterized in that said transfer means (4) comprise first tilting arms (41) equipped with respective first clamps (43) actuated by electric motor-reducers (44) to change between open and closed positions, said first tilting arms (41) being actuated to swing between a first position, in which said first clamps (43), when passing from their open position to their closed position, grasp the tube of sheet material (8) by lateral clamping areas (84a, 84b) close to said cutting means (2) just before they make said transverse cut, and a second position, in which the flattened bag (80), separated , is held by the first clamps (43) in the filling area in a position suitable for transfer to said support means (5).

17. Apparatus, according to claim 16, characterized in that the first tilting arms (41) are fixed to a crossbar (40) driven by an electric motor (45) to rotate in both directions a suitable angle to swing the first swinging arms (41) between their first and second positions.

18. Apparatus, according to claim 17, characterized in that the first tilting arms (41) are slidably coupled along said crossbar (40), and comprise fixing means for fixing the first tilting arms ( 41) to the crossbar (40) in selected positions according to the width of the flattened sheet material (8).

19. Apparatus, according to claim 17, characterized in that the first support (31) is mobile and is mounted so that it can swing towards the second support (32), which is fixed, and to the crossbar (40) is fixed at least one lever (46) arranged to push the first support (31) until it is applied to the second support (32) when the crossbar (40) rotates to swing the first tilting arms (41) from its second position to its first position position, and to pull the first support (31) by means of a strap (47) provided with a sliding opening (48) to separate it from the second support (32) when the crossbar (40) rotates to swing the first tilting arms ( 41) from your first position to your second position.

20. Apparatus, according to claim 16, characterized in that the support means (5) comprise a pair of second tilting arms (51) equipped with respective second clamps (53) actuated by electric motor-reducers (54) to switch between open and closed positions, said second clamps (53), when the second tilting arms (51) are in a resting position, in positions suitable for, when moving from their open position to their closed position, grab The bag (80) by the upper holding areas (83a, 83b) while the first clamps (43) hold the bag (80) by said lateral holding areas (84a, 84b) in the filling area.

21- Apparatus, according to claim 20, characterized in that, said second tilting arms (51) are arranged to freely swing with respect to respective axes substantially perpendicular to the plane of the bag (80) when it is held stretched in said area filling to compensate for a decrease in the transverse length of the rear edge (82) of the bag (80) due to the formation of the opening (86).

22. Apparatus, according to claim 16, characterized in that each of said first clamps (43), together with its drive motor-reducer (44), is mounted on a support (42) linked with its respective swing arm (41) so that it can rotate freely with respect to the axis (42a), and has a center of mass such that said first clamps (43) maintain a substantially horizontal equilibrium position regardless of the angular position of the swing arm (41).

23.- Apparatus, according to claim 1, characterized in that said guiding and advancing means (1) comprise at least one pair of rollers (11, 12) in mutual tangential contact with interposition of the sheet of sheet material (8), at least one of said rollers (11, 12) being connected to drive means that include an electric motor to rotate it.

24. Apparatus, according to claim 23, characterized in that said guiding and advancing means (1) comprise at least one guide element (13) in the form of a tension wire arranged transversely to the direction of advance of the material tube sheet (8) and on which it rests to reduce and / or eliminate an adherent effect produced by a static charge of electricity in the tube of sheet material (8).

25. Apparatus, according to claim 1, characterized in that said foam dispensing means (7) comprise a foam dispensing nozzle (70) located in a stationary position in said filling area, immediately above said opening ( 86) formed in said bag (80) by said opening means (6) while said bag (80) is held by said support means (5).

26. Apparatus, according to any one of claims 1 to 25, characterized in that: said guiding and advancing means (1), cutting means (2) and welding means (3) together form a modular unit of bag formation (101); said support means (5), opening means (6) and closing means (9) together form a modular bag handling unit (102); and said foam dispensing means (7) form a modular foam dispensing unit (103), said modular units (101, 102, 103) being mounted on separate frames easily separable and adapted to operate independently.

27.- Apparatus, according to claim 26, characterized in that said transfer means (4) are incorporated in said modular bag forming unit (101).

28.- Method for forming foam cushions for packaging, where said cushions comprise a bag filled with a synthetic foamy material, characterized in that it comprises the steps of: advancing by means of guiding and advancing means (1) incremental lengths of a tube of flattened sheet material (8) from a coil (10), said tube of sheet material having (8) folded side edges (84) and a closed front transverse edge (81); by means of cutting means (2) make a transverse cut in the tube of sheet material (8) in a position away from said closed leading edge (81) to separate a flattened bag (80) in which the closed leading edge (81 ) constitutes a closed fund; carry out by welding means (3) at least a first welding line (81a) transverse to said sheet of sheet material (8) in a position adjacent to said cut, upstream thereof, in order to form a new edge closed front (81) constituting a closed bottom for a following bag (80); transfer by means of transfer means (4) said separate flattened bag (80) to a filling area; receive by means of support (5) the flattened bag (80) from said transfer means (4), hold it by at least two upper holding areas (83a, 83b) separated at a rear edge (82) thereof and hold it lying in said filling area; separate by opening means (6) at least some areas (85a, 85b) of facing walls of the bag adjacent to said rear edge (82) between said two upper fastening areas (83a, 83b), to form a opening (86) in said bag (80) while being supported by said support means (5); Dispense by means of foam dispensing means (7) a predefined amount of a foamy material into the bag (80) through said opening (86) while the bag (80) is held by said support means (5); and joining said closure areas (85a, 85b) again by means of closure (9) of the opposite walls of the bag (80) next to said rear edge (82) thereof to close said opening (86) while the bag full is sustained by said means of support (5).

29. Method according to claim 28, characterized in that it comprises carrying out said second welding line (3) a second welding line (82a) transverse to said sheet of sheet material (8) in a position adjacent to said cut, downstream thereof, leaving at least a portion without welding (82b) in said second welding line (82a) between the two upper clamping areas (83a, 83b) of the rear edge (82) of the bag (80).

30.- Method, according to claim 29, characterized in that said step of re-joining the areas (85a, 85b) of the facing walls to close the bag (80) comprises carrying out by said closing means (9) a third welding line (82c) next to said second welding line (82a) and downstream thereof, where said third welding line (82c) extends substantially parallel to said un soldered portion (82b) between the two clamping zones upper (83a, 83b), being formed passages (87a, 87b) without welding between the second and third welding lines (82a, 82c) to provide a gas outlet from inside the bag.

31- Method, according to claim 30, characterized in that said step of making a transverse cut in tube of sheet material (8) comprises: trapping a portion of the tube of sheet material (8) between first and second fins (21, 22) arranged on one side of the sheet of sheet material (8) and corresponding first and second runners (23, 24) arranged on the other side, opposite, of the sheet of sheet material (8), where said portion of the tube of material laminar (8) is stretched stretched over a transverse groove (20) between said first and second fins (21, 22) in a space (25) between said first and second runners (23, 24); Y moving a blade (26) inserted through said space (25) and said transverse groove (20) along said first and second fins (21, 22) in interference with the portion of the sheet of sheet material (8) ready there.

32.- Method, according to claim 28, characterized in that said step of separating at least some areas (85a, 85b) from facing walls of the bag (80) to form an opening (86) comprises: moving first and second adherent surfaces (63, 64) to bring them closer together until they are pressed against each other with interposition of said areas (85a, 85b) of the facing walls of the bag (80) adjacent to said rear edge (82); and moving said first and second adherent surfaces (63, 64) to move them away mutually with the areas (85a, 85b) of the facing walls of the bag (80) adhered thereto until forming said opening (86).

33.- Method, according to claim 32, characterized in that it comprises incorporating said first and second adherent surfaces (63, 64) in respective first and second mobile elements (61, 62), and displacing said first and second mobile elements ( 61, 62) a predetermined one-way stretch each time they move from a closed position to an open position, or vice versa.

34.- Bag for forming foam cushions for packaging, where said cushions comprise a bag filled with a synthetic foamy material, said bag (80) being characterized in that it comprises: a tubular portion of flattened laminar material that defines folded side edges ( 84); a first transverse weld line (81a) next to a closed bottom edge (81) constituting a closed bottom; a second welding line (82a) transverse next to an upper edge (82) of the bag (80); and an un-welded portion (82b) in said second welding line (82a) between two upper clamping zones (83a, 83b) suitable for being grasped by upper handling pliers, at least some areas (85a, 85b) being opposite walls of the bag, adjacent to said upper edge (82) between said two upper fastening areas (83a, 83b), adapted to be separated to form a filling opening (86) while the bag (80) is held by said upper handling tongs.

35.- Bag, according to claim 34, characterized in that it is adapted to be closed, once filled, by means of a third welding line (82c) close to said second welding line (82a) and below it, said third welding line (82c) extending substantially parallel to said unbranded portion (82b) between the two upper clamping zones (83a, 83b), passages (87a, 87b) being formed without welding between the second and third lines of welding (82a, 82c) that provide a gas outlet from inside the bag.